NEVA Celebrates National Pi Day With T-Shirts

National Pi Day


Pi, Greek letter (π), is the symbol for the ratio of the circumference of a circle to its diameter. Here are some more facts:

With the use of computers, Pi has been calculated to over 1 trillion digits past the decimal. Pi is an irrational and transcendental number meaning it will continue infinitely without repeating. The symbol for pi was first used in 1706 by William Jones, but was popular after it was adopted by the Swiss mathematician Leonhard Euler in 1737.

Pi Day is celebrated by math enthusiasts around the world on March 14th and Larry Shaw created Pi Day in 1988. The holiday was celebrated at the San Francisco Exploratorium, where Shaw worked as a physicist, with staff and public marching around one of its circular spaces, then consuming fruit pies. The Exploratorium continues to hold Pi Day celebrations.

On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution (HRES 224), recognizing March 14, 2009, as National Pi Day.

(Sources: and

Purchase a Locally-Made T-Shirt!

If you’d like to have a unique t-shirt to wear this year, click the Buy Now button on the right. We offer secure check out through Paypal, or if you’d like to pay by cash or check, you can send payment to:

Pi Day Shirts
15 Beck Street
Newburyport, MA 01950

Shipping is just $0.99 for any order and we’ll mail your shirt(s) within 3 business days.

How Loud Is It?

Source Level, dBA
Military Jet at 100ft 140
Artillery Fire at 10 ft 130
Passengers Ramp at Jet Airliner 120
Discotheque 110
Textile Mill 105
Printing Plant 100
Platform of Subway Station 100
Jackhammer, 15 meter 97
Generator Room 90
Unmuffled Diesel Engine at 130 ft 90
Heavy Truck, 15 meter 85
Concrete Mixer, 15 meter 80
Computer Printout Room 80
Inside Auto, 64km/hr 76
Vacuum Cleaner, 3 meter 70
Freight Train at 100 ft 70
Auto, Pass by, 30 meter 65
Conversational Speech at 3 ft 60
Large Transformer, 15 meter 58
Urban Area 55
Window Air Conditioner 50
Suburban Area 45
Quiet Country Setting 35
Soft Whisper, 2 meter 35
Empty Broadcast Studio 28
North Rim, Grand Canyon 25
Threshold of Good Hearing 10
Threshold of Excellent Hearing – Youths 0

The Problem with Hotels

If you spend time traveling for business, you may be aware of the problem with hotels. Hotels like to give their guests all the creature comforts of a home. In that laudable pursuit, noise happens. Typical hotel noise that I find annoying are the heating and cooling unit in the room, the television sound from the adjacent room, the hum of the mini refrigerator and hallway sounds. These problems can be easily fixed if the equipment manufacturers paid some attention to the acoustical characteristics of their product. Yes, the product might cost slightly more but for a quiet hotel room, I would be willing to pay slightly more. With those issues out of the way, let’s discuss the other not so common sounds that may offend.

Part 1:

I was staying in a well known hotel chain, somewhat upscale, and noticed an unpleasant noise in my room. Looking out the window, I discovered a refrigerator truck parked in the hotel lot. I called the front desk to inquire how long the truck would be in the lot and was told all night as the driver was a guest. Being a frequent flyer at this particular chain, after measuring the noise level and frequencies with my noise meter, I called the 800 number to complain. I must admit they were somewhat surprised that I was able to advise them of the noise level and offending frequencies but the truck was moved to another location.

Part 2:

I recently stayed in a hotel room (another well known chain) and was stunned to hear the person in the next room using the bathroom. Once quiet was restored, I walked into my bathroom and immediately saw the problem. The vent for the exhaust fan was in a location on the wall that indicated I and the person next door shared the same venting equipment. That probably seemed like a good cost-saving strategy to an architect but it allowed perfect sound transmission from one bathroom to another. Not good.


Business travels like quiet hotel rooms. Noise is often the most frequency subject of complaint from guests and needs to be addressed by the hotel groups. Mechanical equipment is often the noise source and transmission from one room to another is another part of the equation. Movie theaters have used sand in between adjacent theaters but the structure is substantial and footprint of the room diminished. Hotels want as many rooms as possible in the square footage of the building. There are acoustic materials available to solve this dilemma and hotels would be wise to investigate how to keep business travelers as well as families quiet and cozy in their rooms. For the hallway noise? A substantial door that fits the frame well and a sign for the door handle that states “Quiet, Please”.

Can You Hear Me Now?

The difference between loudness, sound quality and audibility is interesting. During the dark ages of acoustics, much attention was given to measurements of dB or how loud the sound was. Ordinances were written to limit the dB level at a property line and as long as the measured sound was below the noted dB level, the problem was solved.

Some years ago, equipment manufacturers discovered that if the product had a “pleasant” sound, as described by a focus group”, the product would gain better acceptance in the marketplace. The manufacturers changed the acoustics of the equipment with materials to absorb or mitigate particular frequencies that buyers often found annoying. Particular attention was paid to any mechanical equipment as the low frequency noise was often objectionable. For example, automobile manufacturers discovered buyers believed the car was more durable and of better quality with certain tones from the engine and doors. Therefore, the new parameters of sound included both loudness and sound quality.

More recently, as urban and suburban areas became denser, audibility gained significance. For example, apartments near an office building may be annoyed by the rooftop chiller. When the loudness is measured, the dB level may be very close to the background noise level when the chiller is not in operation. The audibility, however, is discernible as the mechanical parts produce low frequency tones that are clearly heard. Some noise ordinances now, the Department of Environmental Protection for example, measure not only the dB level but any “pure tones” that are produced by the noise source. A pure tone is a frequency that is significantly louder than the adjacent frequencies and, therefore, is very audible.

If you manufacture equipment or have a complaining neighbor, NEVA can assist you in determining how restore the quiet by changing the loudness, sound quality and audibility.

The Quiet Revolution

As the demand for quiet environments has intensified, the acoustics sector has finally responded. Urbanization, faster industrial production and the new culture of privacy in medical facilities and offices have created an insistence for refined acoustic sound levels. As a culture, we want our environments to be quieter, including both loudness and audibility of the sound. Mechanical tones, low frequency sounds, are annoying and present in most human habitats. Heating, air conditioning, ventilation, generators, manufacturing equipment, computer servers, aircraft, subways – all examples of mechanical tones invading our space on a daily basis. In noisy spaces, we may talk louder, increase the volume of the radio or television, wear ear plugs or close a door to escape the tones that interfere with our thinking, writing, productivity or creativity.

Thus, we are beginning the quiet revolution, as we define “quiet” using new parameters. New York City has passed a “Construction Noise Ordinance”. Cambridge Massachusetts has outlawed leaf blowers. The HIPPA Act insists on a patient’s privacy when conversing with a doctor or nurse. Each year, we redefine how we interact with noise in our environments. Each year, Americans and Europeans consider noise one of the most important issues in determining quality of life.

New materials have been developed in response to these demands that now permit acousticians to diminish noise, improve sound quality and reduce low frequency noise without adding substantial weight and thickness to the existing architecture. DuPont LoWave is an example of a new passive technology that permits us to reduce low frequency tones in various environments. LoWave reduces mechanical tones in the 60 to 400Hz range, quieting the mechanical tones we often find intrusive. Previously, we used heavy, thick mass to reduce these tones but the use of mass is often limited by the available space or weight restrictions. For the first time, noise control can attenuate low frequency tones without building concrete walls. 2009 is the year of “Quiet”.